Thornton was at it again Sunday night, scoring 21 of his 27 points after halftime as the Nets went from being threatened in the third quarter to pulling away for a 104-89 victory over the Kings, who dealt him to Brooklyn at the trade deadline.

“If I’m open, I’m going to shoot,” Thornton said.

“When he’s open — shoot,” Deron Williams said. “There’s not a lot of set plays for him. He just finds it in rhythm, in transition or wherever he can get it.”

Facing his former team for the first time since the deal, Thornton helped the Nets bench to a 59-19 advantage. His third game with 20 points and his most-productive outing as a Net saw him shoot 11-of-15 from the field and make 5-of-8 from behind the arc.

“It’s always fun to play your former team and see your homeboys and your teammates from the past,” Thornton said. “But my job was to focus on getting this win and we did.”

“It was great because I know that feeling,” Joe Johnson added. “I know the feeling of being traded. You want to stick it to your former teammates and he did that.”

Thornton played a big hand in Brooklyn erasing the sting from going 4-of-30 from behind the arc Friday in Boston while also helping them win a seventh straight home game.

He also became the sixth Nets player to score 20 or more points in a half this season, joining Johnson and Alan Anderson, who were playfully teasing Thornton for the large amount of postgame attention.

“He’s been huge for us,” Williams said. “What he brings off the bench, his spark, his energy, it’s shooting the basketball. He’s one of the guys that likes insta-hot. He gets one and then it’s like ‘NBA Jam’ — he’s on fire and we’re definitely happy to have him on board.”

Thornton was 3-for-6 when he missed a 3-pointer with 3:33 remaining in the third quarter but then he began heating up. He hit his next seven shots while scoring 13 Brooklyn straight points from the end of the third quarter to midway through the fourth, expanding a 74-65 lead to 87-69.

“Anytime you see the ball go through the goal, you get good confidence about yourself,” Thornton said. “I credit my teammates for finding me in spots I can be effective in. Shots were going down.”

Shots were also going down for DeMarcus Cousins, who finished with 28 points and 20 rebounds.

Most of that damage was done before Kidd decided to use Jason Collins and Andray Blatche together to combat Cousins’ strength. At the time Collins checked in, Cousins was 10-for-12 and the Kings were making a serious dent in a double-digit deficit.

They were within 57-55 after a 3-pointer by Isaiah Thomas and then forged a 57-57 tie on a long jumper by Rudy Gay. The Nets began neutralizing Cousins, who missed a seven-footer and a 15-footer before being forced to the bench when Blatche drew a charge.

The Nets went up 67-61 during a 4:46 stretch of the second half and when Cousins was called for his fourth foul, they expanded the lead thanks to Thornton and Joe Johnson, who scored 11 of his 18 in the third.

“Joe was great,” Kidd said. “I thought he set that tone in that second half — playing through him, being aggressive and scoring the ball and then also finding the open guys. And then he passed the baton because he’s that type of player. He let Thornton go and he carried the torch in that third and fourth quarter.”

Still, it wasn’t a totally good night for the Nets, who played their fifth straight game without Kevin Garnett (back spasms). They may be adding Paul Pierce (right shoulder) and Andrei Kirilenko to their injury report for Monday’s game against Toronto.

Pierce injured his right shoulder while trying to defend a spin move from Jason Thompson. As Thompson put the finishing touches on the play, it appeared his arm made contact with Pierce, who has been dealing with a stinger.

Kirlilenko, who has missed 28 games with back and calf injuries, left midway through the third quarter.